Sadly, for women, it is usually harder for women than men to lose weight/fat.

First, hormones rule. And for women in their 40s, their sex hormones are in flux.

Secondly, as Seejay points out, she is already in the normal range for her height. Fat deposition is largely determined by heredity and hormones - she may not be able to selectively lose the fat in her belly and arms.

However, low carb eating is healthy for *everyone*. I would encourage her to continue eating this way for the improved health, and in time, sense of well-being. Eating an optimum diet will encourage her body to correct itself to optimum shape.

Also, even if eating strictly Low Carb, it is possible to eat more calories than one expends. Many women find they still have to restrict calories with low carb, though probably not as much and with less hunger than if they were eating a low fat diet.